1. Field of the Invention
The present invention relates to a cooling device for a notebook personal computer for cooling an exothermic member such as an electronic element in a personal computer by using a heat pipe for transferring the heat as the latent heat of a working fluid.
2. Related Art
In recent years, there are remarkably widespread the so-called "portable personal computers" of notebook or sub-notebook type. In accordance with the increase in the number of functions or the improvement in the processing speed, on the other hand, the output of an electronic element such as a processing unit is rising year by year. It is, therefore, desired to improve the capacity of a cooling device for cooling the exothermic element. In the prior art, for example, there has been a cooling device which adopts a heat pipe excellent in the heat transfer ability. In the cooling device of this kind, more specifically, the heat pipe has one end portion arranged on the electronic element such as the processing unit acting as a heat source and its other end portion arranged in a heat transferable manner on an aluminum sheet, as arranged in the display for shielding the noise.
When the electronic element generates the heat as the use of the personal computer proceeds, a working fluid in a liquid phase, as confined in the container of the heat pipe, is heated and evaporated. The vapor of the working fluid flows to the other end portion under a lower internal pressure of the container, i.e., to the end portion arranged on the aluminum sheet so that it is derived of the heat and is condensed. This heat is released from the aluminum sheet to the internal space of the display and is dissipated by the natural convection from the inside of the display to the outside. The working fluid having restored the liquid phase is circulated by the gravity or the capillary pressure of a wick toward the end portion, as arranged on the electronic element, of the container until it is heated and evaporated again. As a result, the electronic element is cooled and prevented from being overheated.
Here, the notebook personal computer is earnestly desired to have a small size and a low weight because its major purpose is the portability. This severely restricts the space for the heat pipe to occupy in the internal space of the personal computer case. Usually, the display, as equipped with the aluminum sheet, is so hinged to the personal computer case as can be freely opened/closed (or erected/inclined). When the display is to be employed as the heat dissipating means, the heat transfer means such as the heat pipe has to be so constructed as can be freely bent at the connected portion between the personal computer case and the display. The heat pipe per se is excellent in the heat transfer ability but is required to have a high gas tightness for keeping its characteristics, and it is difficult to manufacture a freely bendable heat pipe.